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Molecular and Cellular Biology, July 2000, p. 5064-5076, Vol. 20, No. 14
Department of Biological Sciences, Columbia
University, New York, New York 10027
Received 1 March 2000/Returned for modification 10 April
2000/Accepted 27 April 2000
We have employed gene targeting coupled with conditional expression
to construct a chicken DT40 cell line in which a tetracycline (Tet)-repressible promoter is exclusively responsible for expression of
cTAFII31, a histone-like TAFII residing in both
the transcription factor TFIID and the histone acetylase complex
PCAF/SAGA. Tet addition resulted in rapid loss of cTAFII31
mRNA and protein, eventually leading to apoptotic cell death.
Significantly, five of six other TAFIIs tested were also
rapidly depleted, but levels of the TATA binding protein and subunits
of PCAF/SAGA were at most modestly compromised. Strikingly,
pulse-labeling experiments indicate that total poly(A)+
mRNA transcription was not significantly reduced after
cTAFII31 depletion, and steady-state levels of several
specific transcripts remained the same or decreased only mildly.
Moreover, activation of c-fos transcription following serum
starvation occurred efficiently in the absence of cTAFII31.
These data, which contrast with comparable studies in yeast, strongly
suggest that cTAFII31 and perhaps other TAFIIs
are not essential for general mRNA transcription in DT40 cells. We
propose that this is due to extensive functional degeneracy in the
highly complex metazoan transcriptional machinery.
0270-7306/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Robust mRNA Transcription in Chicken DT40 Cells
Depleted of TAFII31 Suggests Both Functional Degeneracy
and Evolutionary Divergence
*
Corresponding author. Mailing address: Department of
Biological Sciences, Columbia University, New York, NY 10027. Phone: (212) 854-4647. Fax: (212) 865-8246. E-mail:
jlm2{at}columbia.edu.
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